A suspected tornado tore through Connecticut's largest city Thursday, toppling trees and power lines, shattering windows, and collapsing a building as a powerful line of storms swept across parts of the Northeast.

The office of Bridgeport Mayor Bill Finch reported multiple injuries in the city, and rescuers were searching the collapsed building for anyone trapped inside. Finch declared a state of emergency after the fast-moving system of wind and rain.

Hundreds of bricks shook loose from buildings, trees split in half and crushed cars, and a billboard hung precariously several stories up over Main Street.

Jacqueline Arroyo, 44, said she saw a black cloud and ran inside to her third-floor apartment, where the window exploded. Trees were blown so ferociously they appeared to be coming out of the ground, and people were screaming, she said.

"All the wind started coming inside the house. I heard 'boom, boom!'" she said. "It was so fast but terrifying."

A jail is without power, and there were reports of people stuck in elevators, Finch said. The mayor urged residents to stay indoors and remain calm, and Gov. M. Jodi Rell was on her way to the city.

Rescuers were searching a downtown building after it collapsed during the storm, and state police were sending out a police dog to help search for anyone inside.

A Catholic high school, a museum dedicated to P.T. Barnum and several other buildings also had roof and window damage. Tree limbs and power lines blocked traffic on some roads in Bridgeport, a former industrial and manufacturing center of about 135,000 residents that has taken steps in recent years to revitalize areas downtown and waterfront properties.

United Illuminating reported nearly 11,000 customers without power after the storms, along with about 3,800 customers of Connecticut Light & Power.

There were unconfirmed sightings of a tornado, Finch said. A tornado warning had been issued for the area, but National Weather Service meteorologist Richard Castro said the agency would have to survey the area to confirm that one had hit.

Winds that were part of a powerful storm gusted at 78 mph at Sikorsky Memorial Airport at Stratford and blew over some planes.

The storm weakened as it headed out to Long Island Sound, eastern Connecticut and eastern Long Island, he said.

Severe thunderstorms also drenched downtown Philadelphia with torrential rains Thursday afternoon.

The same system had brought storms to northwestern Ohio Wednesday night, destroying a historic town hall and other buildings in Edgerton and injuring a firefighter.